Pantoprazole, 5-(difluoromethoxy)-2-[(3,4-dimethoxy-2-pyridyl)methylsulphinyl]-1H-benzimidazole, is a H+/K+-adenosine triphosphate (ATP) inhibitor (also known as acid pump or proton pump inhibitor (PPI), is an enzyme present in the gastric parietal cells. It is believed that these drugs are metabolized in the parietal cells to active sulfenamide metabolites that inactivate the sulfhydryl group of the proton pump, thus reducing the hydrogen ion secretion. PPIs are generally lipophilic weak bases with poor aqueous solubility at low pH. Many PPIs are unstable in low pH solutions and undergo rapid acid-catalyzed degradation, and they are relatively stable at neutral or high pH.
The current commercial oral formulations of sodium pantoprazole are single unit coated tablets. See, e.g., U.S. Pat. No. 5,997,903, which describes oral forms of pantoprazole that consist of a core, an intermediate layer and an outer layer. The current coating has a tendency to cause undesirable sticking of the tablet to the gastrointestinal tract.
Multiparticulate formulations, because of their nature of dispersing in the gastrointestinal tract, show a reduced food effect and variability in gastric emptying times, thereby providing for reduced inter and intra subject variability, as compared to single unit tablets (Intl. Journal of Pharmaceutics 140 [1996] 229-235).
Several unsuccessful attempts have been made in the past to develop a multiparticulate formulation of pantoprazole. However, these attempts yielded multiparticulates that were not bioequivalent to tablets, only 70% relative bioavailability was found. Another attempt using different technologies—non-pareil seed coating and extrusion/spheronization, resulted in a product that did not provide the appropriate release in acid conditions. In addition, these attempts yielded product that was unstable, as observed by discoloration, when stored at room temperature.